OTP Expiration time

[Abdullah-khalid]

Hi, great job with the library, is there any option to increse the expiration time of generated OTP?

[uvulpos]

https://github.com/sec51/twofactor/blob/master/totp.go#L109

func makeTOTP(key []byte, account, issuer string, hash crypto.Hash, digits int) (*Totp, error) {
	otp := new(Totp)
	otp.key = key
	otp.account = account
	otp.issuer = issuer
	otp.digits = digits
	otp.stepSize = 30 // we set it to 30 seconds which is the recommended value from the RFC
	otp.clientOffset = 0
	otp.hashFunction = hash
	return otp, nil
}

You call the NewTOTP Function, which calls and returns the makeTOTP Function. So, I would assume if you got the *TOTP back, you could just set the stepSize to something else. BUT I would not recommend you to do this, since the point of TOTP is that it is only valid for 30 seconds.

https://en.wikipedia.org/wiki/Time-based_one-time_password

hope that help